The county next week will claim 1,700 acres of high-mountain forests and sagebrush slopes - the expansive Rose Canyon Ranch - to create the largest tract of preserved open space on the valley's west side.

Once combined with Yellow Fork Park and property from its partner, the Bureau of Land Management, the county's newest wedge of wild land will cover nearly 4,000 acres - about the size of Holladay.

"We had no idea this kind of legacy would be available," said Lorna Vogt, the county's open-space coordinator. "This project sets aside a wild and beautiful portion of our valley for our future generations."

The county announced Wednesday that it would snatch up the ranch property in the rugged Oquirrh Mountains west of Herriman.

The price: $8.7 million. The money comes from a voter-approved $48 million bond, passed in 2006, for parks and open space.

The location is superb, officials say, cobbling together county and federal lands to create a massive recreation area for hiking, horseback riding and back-country bicycling.

The region - it climbs to 7,300 feet along the Salt Lake/Utah county lines - also is home to wild turkeys, cougars and a herd of 750 elk.

"It was a dream come true to have that piece of property still available," Salt Lake County Mayor Peter Corroon said, "especially on that side of the valley where there is such tremendous growth."

He called the purchase a "coup." His environmental policy coordinator, Ann Ober, described it simply as "an opportunity to preserve what's best about this valley."

Officials will establish trail heads, watering holes for horses, picnic areas and, maybe, benches for weary walkers.

Wendy Fisher, executive director of Utah Open Lands, applauded the county's purchase.

"It is probably one of the largest contiguous parcels of land that has been set aside in Salt Lake County," she said. "To have this large of a block of land on the west side is truly amazing."

jstettler@sltrib.com